1. Technical Field
The present invention relates to a key rotation scheme for a Digital Rights Management (DRM) system in a Dynamic Adaptive Streaming over Hypertext transfer protocol (DASH)-based media service.
2. Description of the Related Art
Descriptions contained in this field are merely intended to provide background information related to the present embodiment, rather than describing the configuration of conventional technology.
Entitlement Control License (ECL) is one of methods for content protection when a Dynamic Adaptive Streaming over HTTP (DASH)-based media service is provided. DASH enables media content to be protected based on MPEG Common Encryption (MPEG-CENC) standards. Here, media content is created with encryption based on an encryption key at the most basic level. There are a plurality of elements for classifying the strength of content protection, one of which is to periodically change an encryption key. Periodically changing an encryption key is referred to as “key rotation”. ECL is a license used for a key hierarchy method, which is one of known methods of changing an encryption key for key rotation.
Standards known to date merely describe that “if it is desired to use a key hierarchy method when DASH-based media is encrypted using a key rotation scheme, ECL and Entitlement Management License (EML) may be used, ECL must include an encrypted media decryption key, and EML must include a decryption key required to decrypt the encrypted media decryption key” but do not specify the detailed operation of ECL or EML. In the case of EML, it does not matter if a content security service provider freely operates the EML using his or her own method. However, in the case of ECL, ECL is data that is included in media content and is transmitted through media and a transmission channel, and thus much clearer standardized rules are required.